Ephedra californica recovery

Purpose

To explore ephedra recovery following clipping. Year two in a long-term shrub removal experiment. Aboveground clipping. Panoche Hills Ecological Reserve. Removal done by A. Liczner, A. Filazzola, T. Noble, and M. Westphal. Loss of shrub effects on animals experiment separate from this survey initiated by A. Liczner and completed 2016.

ecoblender

Data

library(tidyverse)
library(plotly)
data <- read_csv("data/EH.recovery.2016.csv")
data
## # A tibble: 20 × 6
##       ID length width height resprout
##    <chr>  <dbl> <dbl>  <dbl>    <int>
## 1   P137   1.90  3.30   0.60        9
## 2   P146   3.40  2.15   0.70       10
## 3  P182*     NA    NA     NA       15
## 4   P197   1.35  0.60   0.63        3
## 5   P200   0.00  0.00   0.00        0
## 6   P217   1.15  1.25   0.85       15
## 7   P245   3.20  2.50   0.80        8
## 8   P271   2.80  2.55   0.71        8
## 9   P273   0.80  0.90   0.55        1
## 10  P303   3.50  2.80   0.60       13
## 11  P444   2.75  0.95   0.88        5
## 12  P452   1.20  0.65   0.90        2
## 13  P462   2.33  0.85   0.70        6
## 14  P544   3.55  2.05   0.85        8
## 15  P614   1.70  1.15   0.43       12
## 16  P615   1.10  1.35   0.85        2
## 17  P618   2.10  0.95   0.70        4
## 18  P621   1.85  0.90   0.65       10
## 19  P651   2.55  2.40   1.00       10
## 20 P183*   1.40  1.20   0.60        6
## # ... with 1 more variables: observations <chr>
data <- data %>% mutate(volume = ((length + width)/2)^3*3.14*(1/3)) %>% arrange(desc(resprout))

EDA

p1 <- ggplot(data, aes(resprout, weight= volume)) + 
  geom_histogram(binwidth = 2, fill = "dodgerblue") +
  xlab("number of shoots resprouted") +
  ylab("relative weighted frequency by volume")
ggplotly(p1)
p2 <- ggplot(data, aes(volume, resprout)) + 
  geom_point(color = "dodgerblue") + 
  geom_smooth(method = lm)
ggplotly(p2)
m1 <- glm(resprout ~ volume, data = data)
summary(m1)
## 
## Call:
## glm(formula = resprout ~ volume, data = data)
## 
## Deviance Residuals: 
##     Min       1Q   Median       3Q      Max  
## -4.9215  -2.0380  -1.0819   0.9429   9.7029  
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)   4.9215     1.1925   4.127 0.000704 ***
## volume        0.2077     0.0845   2.457 0.025032 *  
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## (Dispersion parameter for gaussian family taken to be 14.10428)
## 
##     Null deviance: 324.95  on 18  degrees of freedom
## Residual deviance: 239.77  on 17  degrees of freedom
##   (1 observation deleted due to missingness)
## AIC: 108.09
## 
## Number of Fisher Scoring iterations: 2
anova(m1, test = "Chisq")
## Analysis of Deviance Table
## 
## Model: gaussian, link: identity
## 
## Response: resprout
## 
## Terms added sequentially (first to last)
## 
## 
##        Df Deviance Resid. Df Resid. Dev Pr(>Chi)  
## NULL                      18     324.95           
## volume  1   85.175        17     239.77  0.01399 *
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1